Space shuttle Endeavour and its 747 carrier aircraft soar over the Golden Gate Bridge in San Francisco during the final portion of its tour of California on Friday, Sept. 21, 2012. (AP Photo/NASA, Carla Thomas)

Nichelle Nichols, the actress who portrayed Lt. Uhura on the 1960s televesion series "Star Trek," speaks after space shuttle Endeavour lands aboard a NASA Boeing 747, at the conclusion of its last flight at Los Angeles International Airport on Friday, Sept. 21, 2012. In a few weeks, Endeavour will be towed through city streets to its new home at the California Science Center in downtown Los Angeles. (AP Photo/Reed Saxon)

J.J. Johnston, FAA liasion and coordinator of all the Space Shuttle homecoming flights, waves the U.S. flag from the cockpit as Endeavour taxis to an airline maintenance hangar aboard a NASA Boeing 747, at the conclusion of its last flight at Los Angeles International Airport on Friday, Sept. 21, 2012. In a few weeks Endeavour will be towed through city streets to its new home at the California Science Center in downtown Los Angeles. (AP Photo/Reed Saxon)

Space shuttle Endeavour, atop a modified 747, is followed by two chase planes and a bird as it near Dodger Stadium on Friday, Sept. 21, 2012, in Los Angeles, on a sightseeing tour of California, the last aerial hurrah before retiring to a Los Angeles museum. (AP Photo/Mark J. Terrill)

Space shuttle Endeavour, atop a modified 747, passes the Hollywood sign and the Griffith Observatory as seen from Dodger Stadium on Friday, Sept. 21, 2012, in Los Angeles. Endeavour will be permanently displayed at the California Science Center in Los Angeles. (AP Photo/Mark J. Terrill)

Space Shuttle Endeavour mounted on NASA's Shuttle Carrier Aircraft, passes over the California state capitol on Friday, Sept. 21, 2012, in Sacramento, Calif. Endeavour is making a final trek across the country to the California Science Center in Los Angeles, where it will be permanently displayed.(AP Photo/The Sacramento Bee, Lezlie Sterling)

Former U.S. Rep. Gabrielle Giffords and husband, former astronaut Mark Kelly, watch space shuttle Endeavor fly over Tucson, Ariz., on its way to Los Angeles on Thursday, Sept. 20, 2012. Kelly, Endeavour's last commander, requested that the shuttle pass over Tucson to honor Giffords, who is recovering after suffering a head wound in a shooting rampage last year. (AP Photo/Southwest Photo Bank, P.K. Weis)

The Shuttle Carrier Aircraft with space shuttle Endeavour mounted on top is guided under cranes and trusses in preparation for de-mating, Friday, Sept. 21, 2012, at Los Angeles International Airport. Endeavour, built as a replacement for space shuttle Challenger, completed 25 missions, spent 299 days in orbit, and orbited Earth 4,671 times while traveling 122,883,151 miles. Beginning Oct. 30, the shuttle will be on display in the California Science center's Samuel Oschin Space Shuttle Endeavour Display Pavilion.(AP Photo/Paul E. Alers, NASA)